Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $58.46   7.519%   $62.8556   $62.86   $62.85   $62.90  
  Purchase #2 $213.26   11.227%   $237.2027   $237.20   $237.20   $237.20  
  Purchase #3 $95.26   3.571%   $98.6617   $98.66   $98.65   $98.70  
  Purchase #4 $173.77   9.852%   $190.8898   $190.89   $190.90   $190.90  
  Purchase #5 $160.67   13.335%   $182.0953   $182.10   $182.10   $182.10  
  Purchase #6 $127.97   6.610%   $136.4288   $136.43   $136.45   $136.40  
  Purchase #7 $181.75   11.474%   $202.604   $202.60   $202.60   $202.60  
  7 purchase totals = $1,011.14       $1,110.7379   $1,110.74   $1,110.75   $1,110.80